It is common for a modern production and testing facility to control the particles in the air that circulates within a clean room facility in order to ensure the quality of its output. Whether be it wafer dies, compact discs or memory disk drives, effective fan filter units are needed to not only keep the particle contents within the clean room at acceptable levels but also to circulate the air which the workers breathe.
Such powerful fan filter units create excessive noise however. It is known that the insulation material are lined along the conduit or within the fan filter units to reduce the noise generate by the fan blowers. Over time, however, the particles or fiber from the insulation material are dislodged from the surface and contaminate the clean room facility.
The problem associated with the particle contents in clean room facility is exacerbated in confined space or enclosures such as a multi-story wafer fabrication plant. By confined space, the present invention envisages the height of the ceiling to be less than three meters. Because of the low height clearance, the noise from fan filter units is particularly pronounced.